Abstract：Based on an analysis of 166 heavy mineral samples from the 3rd Member of Ziniquanzi Formation (E1-2z3) in the central southern margin of the Junggar Basin and taking into account such factors as regional structure, climate and sediment characteristics, the authors have reached the following conclusions: the palaeogeographic conditions for the deposition of the 3rd Member of Ziniquanzi Formation were dry, with the development of multi-channel and intermittent braided rivers in the same direction characterized by shallowness, multiple sources and gentle slopes. A number of parallel rivers were developed, moved and extended vertical to the shoreline. Nevertheless, various kinds of sedimentary facies with a fairly great width were spread parallel to the shoreline.